Abstract: The quality of the external air is determined by means of a pollutant sensor. The quality of the internal air is determined by calculation taking account of the air quantities introduced from outside into the internal space. A decision between air supply operation and air recirculation operation is then made on the basis of a comparison of the air qualities inside and outside. The pollutant sensor is preferably located in a casing whose internal space is accessible to gases through an opening which is preferably sealed by a gas-permeable membrane.

Abstract: A ventilation arrangement for the interior of a motor vehicle, having at least a heating or air-conditioning unit. The ventilation arrangement has a fan for air exchange in the interior and a filter for the adsorption of odorous and/or harmful substances contained in the air stream. The filter is designed so that, for the widest possible spectrum of odorous and/or harmful substances, a filter effect is produced which is based on rapid adsorption of the odorous and harmful substances and a gradual desorption thereof with a long time delay. A high short-term concentration of the odorous and/or harmful substances is thus converted by the filter into an extremely low but, instead, long-lasting emission which, with sufficiently extensive dilution, remains below a preset odor threshold or nuisance threshold.

Abstract: A soot burn-off filter including a monolithic filter block made of porous ceramic with a multiplicity of channels which extend in the direction of flow of the exhaust gases of a combustion engine. The channels are sealed alternately at the ends by plugs and are separated from one another by porous partition walls. The partition walls are provided with a catalytic coating and have an increased flow resistance in a region at the downstream end of the filter, the partition walls in this region being of gastight design and the catalytic coating of the partition walls ending in a region upstream of the gastight region of the partition walls.